What's New on the PRR Panhandle Division?

[G3750]

It sounds to me like your switch machines may have worked previously more out of luck than anything else. If the method of communication on the data wire is truly RS-232, then the designers chose the wrong medium. RS-232 is the specification for a point-to-point communication system of up to 25 feet maximum. While it can support (and has supported) much longer distances, the key is "point-to-point," which means ONE transmitter and ONE receiver. Driver and receiver chips designed to this specification are not intended to be placed in a circuit with multiple drops and multiple receivers. Instead, the designers should have used RS-422, (http://en.wikipedia.org/wiki/RS-422) which allows for a multi-drop architecture, and uses differential signalling, as opposed to RS-232's single-ended signalling scheme.

That said, it sounds like the best thing you can do to make and keep your current system working, is to ensure that ALL devices on the network have a solid ground reference. This ground reference is necessary because it is what the devices use to determine what is a "one" and what is a "zero" in the data stream.

Gtfan, I may have mispoken about the protocol used. It might well be RS-422. It's been at least 25 years since I played with these protocols or "dumb terminals" that used them. I don't believe these switch machines have worked just because of good fortune. While an individual switch machine or two has been flaky, the majority have operated first time, every time for years.

Your point on grounding is well taken. Thank you.

George

[gtfan]

If it were RS-422 that they were using, there should be two data wires, not one. RS-422 uses a differential signal, and the the value of the data (one or zero) depends on the plus wire's voltage level with respect to the minus wire. You can't operate a RS-422 network with one data wire. You can, however operate a RS-232 send-only network with one wire, assuming you have a good ground to reference the signal.

The lack of a ground in their drawings indicates to me that they are using only the AC common of the track voltage supply as their ground reference. This is usually not adequate, as it is NOT ground, but an AC common signal, which may or may not be near ground potential. Note that the Command Base power supply is the the only TMCC device that has a 3-prong plug. That is because the command base is a communications device and needs a ground in order to operate properly.

Assuming that they are using this AC common as their signal ground, you should check all your transformers to make sure they are properly phased. Having one out of phase could place enough AC on the common to adversely affect the data wire's ground reference.

[jlong]

George, did you try magic lamps???

Hey John, did you take a close look at the wiring diagram? See those bulbs between the terminal strips on the lefthand side?

They were "magic light bulbs" left over from when I tried DCS. Now they simply tell me that juice is flowing to each of the power districts.

George

George, I missed them
All this talk sounds like network manager talk and baffles the hell out of me.

[G3750]

George, did you try magic lamps???

Hey John, did you take a close look at the wiring diagram? See those bulbs between the terminal strips on the lefthand side?

They were "magic light bulbs" left over from when I tried DCS. Now they simply tell me that juice is flowing to each of the power districts.

George

George, I missed them
All this talk sounds like network manager talk and baffles the hell out of me.

Seriously, when I tried DCS, I went through what were then "Barry's DCS Commandments" and tried to implement them. This would have been 2005-6. The commandments called for equal length wires from a central terminal strip supplied by a TIU channel, so I ran pairs of wires (ALL of them of equal length) from the terminal strip to the track (lots of wasted wire). Ditto on the "magic light bulbs". If the commandments wanted them, I installed them. I finally got tired of hearing that the solution was just around the next bend or over the next hill or would work if I only stood on 1 leg wearing the tinfoil hat. The final straw was hearing people (myself included) get blamed as the cause of the problem when we complained about system reliability.

So I went down to the layout and carefully reworked the power distribution panels to use TMCC. I re-planned the power requirements and wiring changes. When it came time to make the changes, I decided to leave the bulbs in place. I now know if power districts are getting electricity. See, all the yard districts (5, 6, 7, are TMCC only. The mainline and passing siding districts (1, 2, 3, 4) can be run either with TMCC or conventionally. My TPC provides both modes. When I first put power to the layout, yard districts are ON. Pressing the correct key sequence instructs the TPC to bring up the mainline districts in TMCC mode or in Conventional mode. The lights for these district tell me what is / isn't happening.

George

[rogruth]

That is why I still run mine conventionally.

[G3750]

That is why I still run mine conventionally.

I certainly understand and respect that, Roger.

But I have come to really appreciate command control with the ability to run multiple trains, crawling locomotive speeds, and switching operations.

And I firmly believe that this glitch, which is not actually a TMCC issue, will be solved. Z-Stuff components tend to be well engineered, although the Chinese manufacturer has their share of quality control issues. And Dennis Zander does stand behind his products, having called me after business hours to debug an issue and returned all my e-mails. In fact, he and I have a call scheduled tomorrow to debug this. And he's given me a number of things to try before then.

George

[jlong]

Your intentions were good George. DCS belongs in a museum.

[rogruth]

George,

I can see a lot of advantages to Lionels command control.
One of my problems is that my layout is wired for the old block system and I have mostly conventional control locos.
I have three with TMCC.I understand that to run my conventional stuff with TMCC I will need to add block power
controllers of some type and at @$100.00 each I cannot afford that so I stay conventional.
I do not feel confident in rewiring everything.I have no idea what you,gtfan and John are talking about.
I think I should stay with what I know.

[jlong]

A single block power controller will power 4 blocks. You don't need them. You can continue using your existing block switches by powering them with the track power controller instead of powering the block power controller(s). The out put of a track power controller is no different than the output of your transformer (other than the sine wave maybe). You won't understand TMCC until you buy into it. No different than the computer you type on.

[rogruth]

My TMCC locos run OK with TMCC.

I am not able to run conventional with the TMCC controller.
I do know they are NOT operated the same.
It seemed to me that if I had all electrical control panel switches
set the same I should be able to control a conventional loco with
the hand set.I have not been able to get that to happen and
stopped trying about four years ago.I had all of the stuff needed to
make it work but,as stated earlier,was told that I needed some
type of control to every block.I don't know.Not sure I'll try again.

My layout is finished except for small details.Maybe I will have
time to try again.

[G3750]

Your intentions were good George. DCS belongs in a museum.

John, thank you.

DCS is a beautiful concept that has been poorly executed (perhaps up to now). As conceived, DCS has significant advantages over TMCC:

• A more comfortable handheld remote with a screen
• A software menu system displayed on the screen
• Scale Miles Per Hour (SMPH) - a very nice feature that permits realistic multiple locomotive lashups
• Many, many more features that create a realistic railroad experience
• Bi-directional message transmission, permitting a more sensitive and realistic feedback mechanism
• Expandability and bug fixes via software updates
• Ability to control TMCC locomotives

As a 2nd generation command control system, you would expect DCS to have a significant advantage in features and capabilities over TMCC. That's progress. But, it also has its weak points, many of which are fatal flaws (at least for me):

• Signal transmission mechanism is badly engineered; requires nearly perfect conditions to operate
• Poor quality of manufacturing - high ratio of failed boards, cheap componentry selection
• System requires nearly perfect wiring and careful tuning as track complexity increases
• Inadequate documentation from manufacturer because of system complexity (you need a real 200+ page manual)
• Ergonomic design of AIU is poor; it's hard to feed small wires into those closely spaced ports.

I hear (only hearsay) that PS3 is better than PS2 and that the newer TIU hardware is an improvement, but I don't know that personally. And it's taken MTH 10 years and 4 hardware (TIU) revisions to get there.

George

[jlong]

George, are you comparing DCS to TMCC 1 or Legacy? I only ask because I thought Legacy picked up many of the features you described with DCS. I don't own a Legacy outfit so I don't know. You can't always go by what you read on the internet. It's half full of crap. I own only one PS-3 engine and I like the fact they eliminated the battery.

Probably the most reliable system is the system your Marx 666 set uses.

[G3750]

I'm comparing DCS to TMCC. I don't own Legacy or any Legacy engines, so I can't speak for it. I do know that Legacy has many new features and is, in some ways, an attempt to answer DCS. Other than that, I can't say.

Yeah, that Marx 666 hasn't failed in 55 years.

George

[jlong]

I have two Legacy diesels that work fine with TMCC 1. I just can't justify the price tag of a Legacy controller and the added features it unleashes. The KISS principle at work.

[rogruth]

George,

Have you posted your critique of DCS on OGR?

I really can't comment because I have never seen
DCS in use and seldom use the TMCC I have.

I wonder how many will now post their opposite
view from yours.?Yours seemed to be from personal
experience and IMHO not stated in an inflammatory manner.